This invention relates to a method according to the introductory part of claim 1, to a system according to the introductory part of claim 22 for practicing such method using a data processor system, and to a set of instructions for use therein.
Such a system and such a method are known from U.S. Pat. No. 5,283,752. When in-line printing and finishing sheet-like objects—such as in-line printing, combining with inserts, folding, inserting and franking documents within the framework of composing postal items—failures sometimes occur in the finishing process downstream of the printer.
In order to prevent accumulation of printed objects at the output of the printer, it is then useful to stop the supply of printing instructions to the printer. It is a problem here that modern printers contain a considerable memory, in which, in operation, a buffer stock of printing instructions is stored, which printing instructions are processed on demand and with some delay after having been outputted to the printer. If in response to a failure in the equipment for finishing printed objects the supply of printing instructions has been interrupted, a number of sheet-like objects will still be printed in accordance with printing instructions from the buffer stock.
Stopping the printing with a delay leads to paper waste. Objects printed during run-out of the printer and which could not be processed as a result of the failure must generally be removed by hand. Further, objects still printed and delivered after the occurrence of a failure (and before restart of the finishing apparatus) can run up onto the stationary, preceding objects. A potentially large number of objects still printed and delivered after the finishing apparatus has been stopped further makes it difficult to determine the printing instructions that are to be fed first to the printer at restart. Even if a buffer is provided (such as a first-in-first-out buffer for individual reception and delivery of objects as described in European patent application 0 927 693) for intermediate storage of objects between the printer and the apparatus for finishing the printed objects, it is disadvantageous if the number of objects still printed after a failure has occurred and the supply of printing instructions to the printer has accordingly been stopped is very large, since in that case the buffer must have a correspondingly great capacity.